It is often desirable or necessary to monitor the current flow in a magnetic component winding, such as a transformer winding, for alarm or control functions. Such monitoring is frequently accomplished by means of magnetic coupling in order to eliminate the power dissipation incurred in sensing the current with a series resistive element. In one fairly common arragement, the winding whose current is to be monitored has one of its terminal ends threaded through a toroidal magnetic core having a current sensing toroid winding.
In the prior art the toroidal magnetic core with its current sensing toroid winding was mounted external to the periphery of the magnetic component and was either allowed to loosely dangle secured in place only by its electrical connections or was independently mechanically secured to the circuit board to which the magnetic component likewise was secured. This act of mechanically securing the toroidal core to the circuit board required a separate mounting operation to add the sensing device and to connect the leads of the sensing device to the associated sensing circuitry. These operations add considerable cost to the overall circuit assembly process. Frequently the addition of this current sensing device in the prior art incurred a separate hand insertion and mounting of the device on the circuit board.
The existence of the toroidal mangetic core outside of the periphery of the magnetic component further unnecessarily comsumed board mounting space. In some instances where the entire board is potted the potting operation automatically secured the toroid to the cirucit board, and the attachement of the sensing device to the board was therefore simplified. However the sensing leads still needed hand attachment and in addition the sensing device was still outside of the periphery of the magnetic componet.